The present invention relates generally to security devices for preventing the fall of workers employed on scaffolds, ladders and similar hazardous elevated work platforms. More particularly, the invention relates to a security device for connecting a worker's safety belt lanyard to a safety line to arrest the fall of the worker should the work platform fail or should the worker slip from the platform.
In early times, workers employed at elevated work stations relied primarily on the integrity of the work platform for their personal safety. Those employed on movable scaffolds, for example would secure themselves by means of a safety belt and lanyard to the scaffold but were subject to injury should the scaffold itself fail. In recent years, attention to personal safety has increased, culminating in legislated regulations which specify the neccessary safeguards to be employed in hazardous activities. For those exposed to the inherent danger of falling from elevated work platforms, it is now standard practice to provide separate personal safety lines completely independent of the work platform to which the worker is attached by a lanyard and safety belt. In the event of a platform failure or the worker's slippage from the platform, the safety line will prevent the worker from falling.
The device connecting the worker's lanyard to a safety line must when released automatically station itself on the line and provide a mechanism for clamping the line securely under the weight of the worker should the worker fall. The device further should be readily adjustable along the line to accommodate changes in the worker's elevation, for example as he rises or descends on a motorized scaffold. Another desired feature of such device is that it be attachable and releasable from a standing part of the line without having to thread the entire line through it for each application.
Devices previously proposed for this purpose have, for the most part, been designed to carry out the above described functions but the mechanisms employed have suffered from undue complexity, inadequate rope gripping capability, cumbersome operating mechanisms for attaching or releasing the device to a line or other shortcomings. For example, a number of prior devices have utilized one or more pins which must be pushed through aligned bores in separable parts of the device to attach the device to a line. Not only can the alignment of parts be difficult and time consuming, but the improper securing of the pins as well as unnoticed pin wear may adversely affect the security of such devices. In addition, prior devices have to a large degree operated in a fall situation by applying a severe pinching action at a single concentrated point on the line with a consequent danger of chafing or cutting the line.